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JavaScript Object-Oriented JavaScript (2015) Constructor Functions and Prototypes Making the UI Work

marckaljonp
marckaljonp
14,079 Points
Posted by marckaljonp
marckaljonp
14,079 Points

The 'Next' and 'Stop' buttons are not working.

I recreated what the instructor demonstrated on the vid and can't find what I did wrong. Two of the three buttons aren't working - 'Next' and 'Stop'. Thanks in advance!

index.html 
<!DOCTYPE html>
<html>
<head>
    <title>Treetunes</title>
    <link rel="stylesheet" href="style.css"/>
</head>

<body>

    <div>
        <h1>Treetunes</h1>

        <ol id="playlist">
        </ol>
        <button id="play">Play</button>
        <button id="next">Next</button>
        <button id="stop">Stop</button>

    </div>

    <script src="playlist.js"></script>
    <script src="song.js"></script>
    <script src="app.js"></script>

</body>

</html>
app.js 
var playlist = new Playlist();

var hereComesTheSun = new Song('Here Comes the Sun', 'The Beatles', '2:54');
var walkingOnSunshine = new Song('Walking On Sunshine', 'Katrina and the Waves', '3:43');

playlist.add(hereComesTheSun);
playlist.add(walkingOnSunshine);

var playlistElement = document.getElementById('playlist');

playlist.renderInElement(playlistElement);

var playButton = document.getElementById('play');
playButton.onclick = function() {
    playlist.play();
    playlist.renderInElement(playlistElement);
}

var nextButton = document.getElementById('next');
nextButton.onclick = function() {
    playlist.next();
    playlist.renderInElement(playlistElement);
}

var stopButton = document.getElementById('stop');
nextButton.onclick = function() {
    playlist.stop();
    playlist.renderInElement(playlistElement);
}
playlist.js 
function Playlist() {
    this.songs = [];
    this.nowPlayingIndex = 0;
}

Playlist.prototype.add = function (song) {
    this.songs.push(song);
};

Playlist.prototype.play = function () {
    var currentSong = this.songs[this.nowPlayingIndex];
    currentSong.play();
};

Playlist.prototype.stop = function () {
    var currentSong = this.songs[this.nowPlayingIndex];
    currentSong.stop();
};

Playlist.prototype.next = function () {
    this.stop();
    this.nowPlayingIndex++;

    if (this.nowPlayingIndex === this.songs.length) {
        this.nowPlayingIndex = 0;
    }

    this.play();
};

Playlist.prototype.renderInElement = function(list) {

    list.innerHTML = '';

    for (var i = 0; i < this.songs.length; i++) {
        list.innerHTML += this.songs[i].toHTML();
    }

};
song.js 
function Song(title, artist, duration) {
    this.title = title;
    this.artist = artist;
    this.duration = duration;
    this.isPlaying = false;
}

Song.prototype.play = function() {
    this.isPlaying = true;
};

Song.prototype.stop = function() {
    this.isPlaying = false;
};

Song.prototype.toHTML = function() {
  var htmlString = '<li';

  if (this.isPlaying) {
    htmlString += ' class="current"';
  }

  htmlString += '>';
  htmlString += this.title;
  htmlString += ' - ';
  htmlString += this.artist;
  htmlString += '<span class="duration">';
  htmlString += this.duration;
  htmlString += '</span></li>';

  return htmlString;
};

1 Answer

marckaljonp
marckaljonp
14,079 Points
marckaljonp
marckaljonp
14,079 Points

Got it.

app.js 
var playButton = document.getElementById('play');
playButton.onclick = function() {
    playlist.play();
    playlist.renderInElement(playlistElement);
}

var nextButton = document.getElementById('next');
nextButton.onclick = function() {
    playlist.next();
    playlist.renderInElement(playlistElement);
}

var stopButton = document.getElementById('stop');
stopButton.onclick = function() {
    playlist.stop();
    playlist.renderInElement(playlistElement);
}